Electron-hole mixing-induced fine structure in alkaline earth hexaborides leads to lower energy (temperature) scales, and thus stronger tendency toward an excitonic instability, than in their doped counterparts (viz. Ca(1-x)La(x)B(6), x=0.005), which are high Curie temperature, small moment ferromagnets. Comparison of Fermi surfaces and spectral distributions with de Haas - van Alphen (dHvA), optical, transport, and tunneling data indicates that SrB6 remains a fermionic semimetal down to (at least) 5 K, rather than forming an excitonic condensate. For the doped system the Curie temperature is higher than the degeneracy temperature.
@article{arxiv.cond-mat/0003201,
title = {Electronic Fine Structure in the Electron-Hole Plasma in SrB6},
author = {C. O. Rodriguez and Ruben Weht and W. E. Pickett},
journal= {arXiv preprint arXiv:cond-mat/0003201},
year = {2009}
}
Comments
Four two-column pages, three postscript figures. Phys. Rev. Lett. (April 2000, in press)